Cast explosive composition



nited States CAST EZQLOSIVE COMPOSITION No Drawing. Continuation ofapplication Serial No. 72,996, January 26-, 1949'. This applicationSeptember 8, 1953, Serial No. 379,080

6 Claims. (Cl. 52-7) This invention relates to high density explosivecharges, particularly of the cast type, having particular advantages inproperties because of their novel compositions.

This application is a continuation of my copending application SerialNo. 72,996 filed January 26, 1949, now abandoned.

Explosive compositions comprising essentially blends of a low meltingexplosive compound such as trinitrotoluene with one or more inorganicnitrates have found important applications, both civil and military.Because of the low fusion point of trinitrotoluene, this compound isWell adapted for use in castexplosives, which, because of their highdensity, make possible the attainment of high bulk strength. Whereastrinitrotoluene by itself is highly deficient of oxygen, its blendswithammonium nitrate or other inorganic nitrate are more nearly balancedwith respect to oxygen; Amatol-type compositions, for example, havefound important uses, containing between 40 and 80 parts of ammoniumnitrate and 60' to 20 parts trinitrotoluene by weight.

Thorough incorporation of the solid ammonium nitrate With the moltentrinitrotoluene is necessary, prior to casting, if satisfactory resultsare to be obtained. Since the mutual solubility of the two materials islow, there is danger of segregation of the components, which. wouldresult in a lack of uniformity in composition and propagating power.With mixtures relatively low in the fusible component, a disadvantage isencountered from poor fiowing properties of the dispersions.

An object of the present invention is a high explosive compositioncomprising an inorganic nitrate and an organic explosive compound of afusion point below 100 C., said composition being characterized bymarkedly improved flowing properties at temperatures at which the lowmelting compound is in molten condition. A further object is such acomposition comprising ammonium nitrate and trinitrotoluene. A stillfurther object is a composition of the nature described, in which theimproved flowing properties have resulted from the inclusion of a novelingredient in small proportions. A further object is a blend of theaforementioned ingredients, in which the tendency to segregation hasbeen reduced prior to solidification. Additional objects will bedisclosed as the invention is described in more detail in the following.

I have found that the foregoing advantages are accomplished when Iformulate an explosive composition comprising an inorganic nitrate,trinitrotoluene, and a small percentage of a monobasic fatty acid havinga melting point below 100 C. and containing at least eight carbon atoms.While I do not wish to be limited as to the method of preparation,desirably the major ingredients will be preheated separately and blendedat a temperature at which the TNT is in molten condition. Ammoniumnitrate is the preferred inorganic nitrate, or mixtures of this withsodium nitrate, and stearic or palmitic acid the fatty acid.

While different procedures may be followed in the prepatent aration ofexplosive charges according tothe invention, the following was foundsatisfactory and will be understood to be illustrative only and notlimiting in any way.

Example 1 Ammonium nitrate in the amount of 71.8 parts by weight wasintroduced into a mixing apparatus. in which agitation was provided. byrevolving blades, and 02' part of stearic acid was added. The mixturewasheaded for a short time at a temperature between 70 and C.Subsequently, theammonium nitrate was introduced: into a grainingkettle, and 35.0 parts of molten trinitrotoluene was then addedgradually, the latter being. at a temperature above C. Thoroughincorporation of the ingredients was effected, the temperature of themixture being, maintained around 85 C. The composition was then pouredinto large-diameter paper tubes of sturdy structure, for example 5 in.in diameter by 16in. length, and the cartridges were closed by suitablycrimping the open ends. The cast explosive had. a density of around 1.60g./ cc.

of ammonium nitrate and trinitrotoluene by themselves, with no fattyacidadditive, was not truly pourable, though wetin appearance.

Example 2 Following the procedure described in Example 1, the followingcompositions were prepared:

Composition A. B O D E F Percent Percent Percent Percent Percent 34. 0 33-1. 0 34. 0 34. 0 15. 0 15. 15.0 36. S 36. 8 20. 0 20. 0 20. 0 30.0 30;0 30. 0 26. 7 2G; 7 0.98 0. (l. 9 1.0 l; 0 Stearic Acid; 0. 02 0.05 O.1 1. 5 2. 5

*Not more than 20% held on 35 mesh screen and from 15-35% passing meshscreen.

Not more than 15% held. on 14 mesh screen, 30-55% hcldon fitlmoshscreen, and not more than 5% passing e 35 mesh screen.

The results were as follows: w 7

Composition. A. Sofa; slushy (like dry appearingpple. sauc r i y. not;smo h. Forme m nds. 1, in. in height while being loaded'into shell.Shells were bounced to give a full shell, the average weight of a 4 x 12inch shell was 8 lb. 12 /2 oz.

Composition B. More creamy and smooth than A; more pourable and fluid.Flowed, and severe bouncing was not required to fill shell 4 x 12 in.shell average weight8 lb. 15 oz.

Composition C. More creamy andsmooth than B. Gave smooth surface onpouring into shell without any bouncing. 4 x 12 in. shell averageweight-8 lb. 14 oz.

Composition D. Very creamy and fluid. Excellent pouring properties. 4 x12 in. shell average weight, 8 lb. 13 oz.

Composition E. Readily pourable. average weight, 8 lb. 13.2 oz.

Composition F. Not pourable-very slushy. 4 x 12 in. shells loaded bybouncing had an average weight of 8 lb. 9.7 oz.

The foregoing example illustrates the criticality of maintaining thefatty acid added within specific limits, i. e., between 0.01 and 2.0% byweight of the final composition, since excess fatty acid, as exemplifiedin composition F, reduces pourability. The optimum amount of fatty acidrequired for any composition will vary according to the amount of TNTpresent, the fineness of the ingredient, the moisture content of theingredients, etc.

The explosives of the present invention consist mainly 4 x 12 in. shellWhereas the explosive mixture described was. very fluid and pourable, ablend of the same proportions.

of a .blend of trinitrotoluene with an inorganic nitrate. Ammoniumnitrate is the preferred inorganic nitrate because of its inherentproperties as an explosive compound when properly primed and especiallywhen blended with a sensitizing ingredient, whereby substantial oxygenbalance is attained or approached. Other inorganic nitrates may bepresent, for example sodium nitrate, which may be present as the onlynitrate or together with ammonium nitrate. Many other inorganic nitratesmay also be used, such as calcium nitrate, lead nitrate, etc. Additionaloxidizable ingredients may be present also, if desired, such asferrosilicon, aluminum, dinitrotoluene, paraffin, starch, and the like.

Various fatty acids, singly or in mixtures, are available and suitablefor use in the compositions, one requirement being that the fatty acidshave a melting point below 100 C. so that they will be in liquid form atthe temperature of incorporation and pouring. I find it desirable thatthe acid employed be one containing at least eight carbon atoms.Examples of fatty acids satisfactory for use are stearic acid, palmiticacid, oleic acid, lauric acid, and the like. Stearic acid is ourpreferred additive.

While a relatively wide range of compositions is possible, it will beunderstood that a particularly important field will be in ranges wherethe trinitrotoluene is present in relatively low percentages, such thatflow properties of the molten mixtures require consideration. The fattyacid will be present in amounts between 0.01% and 2% by weight of thecomposition. The explosive charges according to the invention willpreferably be within the composition limits by weight of 50-80% ammoniumnitrate, 5020% trinitrotoluene, and 0.01- 2.0% fatty acid.

The explosives of the present invention have definite advantages overprior art compositions, particularly with respect to flowing properties.It is realized that, in shell filling operations, mixtures containing aslow as 20% trinitrotoluene have been used, but such compositions had tobe forced into the shell by the use of pressure, the molten portionserving substantially as lubricant. The compositions described herein,however, allow mixtures to be poured that otherwise would not flow orcause difliculty pourable mixtures to flow freely.

It will be understood that the invention is not limited to size ofcartridges, and the dimensions of these may vary from those of thesmaller dynamite cartridges to the larger quarry sizes, for example 5in. by 24 in. in dimensions. If desired, a plurality of cartridges maybe used, and the nature of the present compositions would allow novelmethods of forming the explosive column. Prior to solidification, forexample, projections in the form of books, bars, or various shapedobjects may be inserted into the molten mixture, which become firmlysecured on solidification. At the other end of the same cartridge, apreformed cavity or other device secured in place during solidificationcould be provided, whereby the assembly of various cartridge units wouldbe facilitated. In a similar manner, lowering arrangements could beprovided, comprising embedded arms of twisted metal or other material.

The invention has been described at length in the foregoing. It will beunderstood, however, that various modifications in the details ofcompositions, procedures, and attachments may be introduced withoutdeparture from the spirit of the invention. I intend to be limited onlyby the following claims.

I claim:

1. An explosive charge comprising a cast blend of between and 20% ofsolid trinitrotoluene, between 50% and of at least one solid granularinorganic nitrate distributed throughout the trinitrotoluene, and amonobasic fatty acid containing at least eight carbon atoms and having amelting point below C., said fatty acid being present in an amountbetween 0.01% and 2%.

2. The explosive charge of claim 1, in which the inorganic nitrate isammonium nitrate.

3. The explosive charge of claim 1, in which the fatty acid is stearicacid.

4. The explosive charge of claim 1, in which the inorganic nitrate issodium nitrate.

5. The explosive charge of claim 1, in which the fatty acid is palmiticacid.

6. The explosive charge of claim 1, in which the fatty acid is oleicacid.

References Cited in the file of this patent UNITED STATES PATENTS1,659,449 Snelling et al. Feb. 14, 1928 2,048,050 Baker July 21, 19362,055,403 Crater Sept. 22, 1936 2,345,582 Carey Apr. 4, 1944 2,356,149Davis Aug. 22, 1944 2,385,135 Holmes Sept. 18, 1945 2,409,919 WhetstoneOct. 22, 1946

1. AN EXPLOSIVE CHARGE COMPRISING A CAST BLEND OF BETWEEN 50% AND 20% OFSOLID TRINITROTOLUENE, BETWEEN 50% AND 80% OF AT LEAST ONE SOLIDGRANULAR INORGANIC NITRATE DISTRIBUTED THROUGHOUT THE TRINITROTOLUENE,AND A MONOBASIC FATTY ACID CONTAINING AT LEAST EIGHT CARBON ATOMS ANDHAVING A MELTING POINT BELOW 100* C., SAID FATTY ACID BEING PRESENT INAN AMOUNT BETWEEN 0.01% AND 2%.